The subject matter of the present invention is a device and a method for testing tablets. The device for testing tablets includes a test chamber, which has a crusher jaw and a counter-jaw opposite the crusher jaw. The device has a movable sheet metal strip, which is configured to position a tablet for testing. The longitudinal axis of the movable sheet metal strip is aligned at an angle of less than 90° relative to the longitudinal axis of the direction of movement of the crusher jaw and the direction of movement of the sheet metal strip corresponds to the longitudinal axis of the sheet metal strip.
As part of the quality control of tablets, it is necessary to check their properties such as length, width, breaking strength and weight. The German Pharmacopoeia contains the relevant legal provisions. If possible, this process should be performed automatically, so that a large number of tablets can be checked within a short time. In addition, it must be ensured that tablets of different shapes and sizes can be positioned correctly to allow error-free measurement. Several devices and methods are known in the prior art that are suitable for this purpose.
German Patent DE 197 33 436 C2 describes a tablet testing device for testing oblong tablets. Here, the tablets to be tested are first conveyed by a feeder to a balance and then from the balance onto a transport device. The tablets are hereby placed on the transport device in a defined position so that further tests can take place. The correct orientation of the tablet when placed on the transport device is accomplished in that the balance bowl has a bottom in the form of a groove. The bottom ensures that the oblong tablets are appropriately aligned. In addition, a stumbling block, for example a wedge, may be located on the transport device, which is provided for the case that the tablet falls onto the transport device with its head side. In this case, the stumble block causes the tablet to tilt to its long side. According to this invention, a correct orientation of a tablet is effected, however, upon its transfer through the groove the tablet is exposed to considerable forces that may damage the tablet.
German Patent DE 10 2006 004 215 B4 discloses a break strength tester for tablets of different shapes and sizes. In order to align the tablets, two counter-rotating, juxtaposed centering rollers are used here. When an oblong tablet is placed on the rollers, their rotation causes the oblong tablet to become oriented longitudinally between the rollers. Subsequently, the strength can be tested by a crusher jaw. In order to enable alignment of tablets of different shapes and sizes, the device is equipped with a pivoting positioner, which can align the rollers differently. The alignment is fast, but the use of rollers after a break test makes the device difficult to clean.
The utility model application DE 298 24 199 U1 discloses a system for carrying out hardness tests on specimens, using an alternative approach. In this case, the tablet is placed on a test bench, but then no alignment of the tablet is performed. Instead, the alignment of the specimen is determined by a device for detecting the position. Then, a pressure piston and an abutment, which are used for the hardness test of the tablet, are aligned accordingly, so that the tablet can be tested. However, this invention requires a complicated and expensive construction, which must include means for image recognition.
PCT publication WO 2013/061223 A2 discloses a method and a device for testing tablets, which aligns the tablets with the aid of a pivotable rocker. The tablet is hereby placed on the initially horizontal rocker, which then performs a pivot movement. As a result of gravity and the pivot movement the tablet aligns with a positioning surface. The positioning surface in this case has a concave shape, which runs along the shape defined by the movement of the rocker. In addition, to assist in the correct orientation of the tablet, the pivotable rocker may be inclined at an angle relative to the positioning surface, or may have an additional device on the side opposite the positioning surface, which performs a pre-alignment of the tablet. After positioning and return of the rocker to a horizontal position, the tablet is tested. Since in this case the positioning is done under the influence of gravity and the rocking motion must be carried out at a sufficient speed, it cannot be ruled out that excessive forces may act on the tablet during orientation.